Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BMS237 - Advanced Developmental Biology > Lecture 20 > Flashcards

Lecture 20 Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What is the significance of the equator that runs through the neurocrystalline lattice structure of the Drosophila eye

A

The equator is a line of mirror symmetry that runs through the centre of the eye where the R7 indents of each surrounding ommatidia is positioned so as to face it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Roughly how long is it between successive induction of the photoreceptors of the ommatidia

A

2 hours

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How is the lens of the Drosophila eye formed

A

The cones cells of the ommatidia secrete the overlying lens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Within which cells of the ommatidia are the UV-sensitive pigments contained in

A

R7

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Other than eyeless, list some of the other genes involved in specification of the eyes

A

Twin of eyeless, eyegone, sine oculis, optix and Dachshund

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Which cells of the ommatidia are the first to form

A

R8

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe the organisation of the rhabdomeres within the ommatidia

A

R1 – R6 cells are organised around the outside of the ommatidia whilst R7 and 8 are present in the centre. R8 is stacked on top of R7

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

In which cells of the ommatidia is sevenless expressed in

A

R8, R1, R6, R4, R3 and R7 as well as in cone cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Wild type Drosophila are phototactic with a preference for UV light, what is seen in R7 mutants

A

They will go towards white (visible) light due to an inability to see UV light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Where do the axons of the outer photoreceptors (R1-R6) project to

A

The lamina

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe the structure of the Drosophila eye

A

Drosophila eyes are referred to as ocelli or orientation eyes as they don’t image as such. Each eye consists of 800 ommatidia or simple eye subunits orientated at angles to eachother to increase the size of the visual field.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the name of the structure where the axons of the R7 and R8 neurons cross over

A

Optic chiasm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Which two cells are then recruited after the R8 cell has been specified

A

R2 and R5

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

R6 and R1 are then recruited before R7 is specified last, T or F

A

T

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the name of the EGF receptor ligand secreted by R8, 2 and 5 that leads to subsequent recruitment of cells

A

Spitz

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Neurons in the eye are mapped in the same spatial orientation as the photoreceptors in the brain, T or F

A

T

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What type of protein is boss

A

Bride of sevenless is a membrane-tethered ligand specific for sev

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

In which cell(s) of the ommatidia is boss expressed in

A

R8

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is seen in mice with a homozygous mutation in the gene that specifies eye development

A

Small eyes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

If boss gene function is lost in R8, what is observed

A

R7 will not develop

21
Q

Explain how sev and boss interact to dictate R7 development

A

Boss binds to sev and initiates a signal transduction cascade in the future R7 cell that is homologous to the Ras/MAP Kinase pathway. Son of sevenless (sos) links the sevenless RTK to the Ras protein by binding via its SH3 domain

22
Q

Flies with mutant R1, 2 and 3 wont develop R7 is R8 isnt present, T or F

A

T – having wild type R1, 2 and 3 is not sufficient to generate an R7

23
Q

What is the morphogenetic furrow and what is its role in development of the Drosophila eye

A

The morphogenetic furrow is a line that starts in the posterior eye disc in the first/second instar and sweeps across anteriorly with newly formed photoreceptors forming behind it

24
Q

What is the term given to a gene that is both sufficient and necessary to dictate the formation of particular structures

A

Master regulatory genes

25
Q

How are the R8 photoreceptors specified to form

A

Notch-delta signalling between the cells within the morphogenetic furrow acts as a lateral inhibition mechanism to space future R8 cells

26
Q

The inhibition caused by the R8 cell is not just lateral but moves as the morphogenetic furrow does, T or F

A

T

27
Q

Which gene must be expressed by the R8 cell in order to generate R7

A

Bride of sevenless

28
Q

Which paired box transcription factor gene determines eye development in vertebrates

A

Pax6

29
Q

Notch-delta signalling is involved in specification of the R8 cell. Which Notch ligand is used

A

Serrate

30
Q

Homozygous mutants for Pax6 die perinatally with no eyes having developed, T or F

A

T

31
Q

Retinal neurons cross over in a structure called to optic decussation, T or F

A

­F – they cross in the optic stalk

32
Q

Bride of sevenless and sevenless are two genes identified to be involved in the ability to Drosophila to perceive light. What is seen in sev and boss mutant flies

A

They will move to be in white light over UV light as opposed to the other way around as is seen in wild type

33
Q

Pax6 has been determined to be both necessary and sufficient to dictate eye development, what is the experimental evidence for this in Drosophila

A

Misexpression of human Pax6 in Drosophila leads to the development of ectopic eyes throughout the fly

34
Q

What are the results of mutations in Pax6 in humans

A

Aniridia – loss of the iris

35
Q

What is the role of the pigment cells in the ommatidia

A

The pigment cell lattice optically insulates each unit eye ensuring that only light entering each subunit is coming from directly in front of it

36
Q

What can be said about the cell division seen ahead of, within and behind the morphogenetic furrow

A

Ahead of the morphogenetic furrow the cells are dividing, within the furrow the cells have arrested in G1 of the cell cycle. Behind the morphogenetic furrow there is limited cell division

37
Q

What is the significance of using notch-delta signalling in lateral inhibition

A

Notch delta signalling uses transmembrane ligands which limits the distance over which it can act to a single cell diameter

38
Q

Explain the mechanisms present that act to specify R7

A

The boss signal restricted to apical membrane of R8 cell so that not all sev-expressing cells are exposed to boss. Seven-up (and rough) transcription factors are produced in the other photoreceptors and inhibit sevenless signalling

39
Q

Sev and boss genes can be removed from R1-6 without causing loss of R7 specification, T or F

A

T

40
Q

Where do the axons of the inner photoreceptors (R7 and R8) project to

A

The medulla

41
Q

What type of protein is sevenless

A

RTK

42
Q

What causes the appearance of the morphogenetic furrow

A

The morphogenetic furrow is caused by a shortening of the columnar epithelial cells

43
Q

What is the name of the invertebrate homologue of the gene that determines eye development

A

Eyeless

44
Q

Vision is extremely important to flies. What percentage of the fly brain is dedicated to visual processing

A

¾

45
Q

Sev is absolutely required in R8, T or F

A

F – sevenless is absolutely required in R7, bride of sevenless is absolutely required in R8

46
Q

Describe the organisation of each subunit of the Drosophila eye

A

Each ommatidia contains around 20 different cells, 8 photoreceptors, 2 primary, 6 secondary and 3 tertiary pigment cells. The photoreceptors are arranged into light sensitive structures known as rhabdomeres. Each ommatidia also has a bristle, neuron socket and sheath cell

47
Q

Pax6 is a highly conserved homeobox containing transcription factor, T or F

A

T

48
Q

Differentiation of the columnar epitehial cells into photoreceptors is seen in front of and within the morphogenetic furrow, T or F

A

F - Within and behind the furrow the first signs of differentiation are seen

BMS237 - Advanced Developmental Biology (32 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions